This study investigates factors that affect usage changes in mobile data services (MDS). First, we conducted an exploratory study based on 378 survey responses to learn about important decision factors of MDS usage. It revealed a discrepancy between the forces influencing usage increase and those of usage decrease. Based on the findings from the exploratory study and Hertzberg?s two-factor theory, we postulated information quality as the motivator and system quality as the de-motivator of MDS usage. Then, we undertook a confirmative study on the respective roles of these factors in encouraging and discouraging the usage of MDS. We proposed a research model and empirically tested our hypotheses with partial least square (PLS) analysis based on 478 responses from MDS users. Information quality (as a motivator) was positively associated with MDS usage increase, but system quality (as a de-motivator) was not. Also, system quality was negatively associated with usage decrease, but information quality was not. Last, their association was partially moderated by the type of motivation for using MDS. Information quality had a stronger influence on MDS usage increase when the main motive was utilitarian rather than hedonic.